In recent years reduced activation ferritic martensitic steel has been proposed as the plasmafacing material in remote regions of the first wall. This study reports the erosion and deuterium retention behaviours in CLF-1 steel exposed to deuterium (D) plasma in a linear experimental plasma system as function of incident ion energy and fluence. The incident D ion energy ranges from 30 to 180 eV at a flux of 4 x 10(21) D m(-2) s(-1) up to a fluence of 10(25) D m(-2). SEM images revealed a clear change of the surface morphology as functions of incident fluence and impinging energy. The mass loss results showed a decrease of the total sputtering yield of CLF-1 steel with increasing incident fluence by up to one order of magnitude. The total sputtering yield of CLF-1 steel after 7.2 x 10(24) D m(-2) deuterium plasma exposure reduced by a factor of 4 compared with that of pure iron, which can be attributed to the enrichment of W at the surface due to preferential sputtering of iron and chromium. After D plasma exposure, the total deuterium retention in CLF-1 steel samples measured by TDS decreased with increasing incident fluence and energy, and a clear saturation tendency as function of incident fluence or energy was also observed.

The structural behavior of polycrystalline perovskite SrTiO3 under 400 keV Ne2+ ion irradiation at both liquid nitrogen (LN2) and room temperature (RT) has been investigated. The grazing incident X-ray diffraction technique was applied to examine the radiation-induced structural evolution. The radiation behavior of SrTiO3 depends strongly on the irradiation temperature. At LN2 temperature, the samples exhibit significant lattice swelling and amorphization, whereas at RT, the lattice swelling is much less conspicuous and no amorphization is detected even at the highest irradiation dose of 5.0 dpa. Nevertheless, Ne2+ irradiation induces peak splitting in XRD patterns at both temperatures. Furthermore, first-principle calculations have been performed with VASP, involving possible defect types, to identify which defect is responsible for the radiation effect of SrTiO3. The results reveal that the oxygen vacancy defect is the most likely to contribute to the radiation behavior of SrTiO3.

An all-optical scheme is proposed for studying laser plasma based incoherent photon emission from inverse Compton scattering in the quantum electrodynamic regime. A theoretical model is presented to explain the coupling effects among radiation reaction trapping, the self-generated magnetic field and the spiral attractor in phase space, which guarantees the transfer of energy and angular momentum from electromagnetic fields to particles. Taking advantage of a prospective similar to 10(23) W cm(-2) laser facility, 3D particle-in-cell simulations show a gamma-ray flash with unprecedented multi-petawatt power and brightness of 1.7 x 10(23) photons s(-1) mm(-2) mrad(-2)/0.1% bandwidth (at 1 GeV). These results bode well for new research directions in particle physics and laboratory astrophysics exploring laser plasma interactions.

We review He ion induced radiation damage in several metallic multilayer systems, including Cu/V, Cu/Mo, Fe/W, and Al/Nb up to a peak dose of several displacements per atom (dpa). Size dependent radiation damage is observed in all systems. Nanolayer composites can store a very high concentration of He. Layer interfaces promote the recombination of opposite type of point defects and hence reduce the accumulative defect density, swelling, and lattice distortion. Interfaces also alleviate radiation hardening substantially. The chemical stability of interfaces is an important issue when considering the design of radiation tolerant nanolayer composites. Immiscible and certain miscible systems possess superior stability against He ion irradiation. Challenge and future directions are briefly discussed.

The dependence of the width of void-denuded zones (VDZs) on grain boundary (GB) characters was investigated in Cu irradiated with He ions at elevated temperature. Dislocation loops and voids formed near GBs during irradiation were characterized by transmission electron microscopy, and GB misorientations and normal planes were determined by electron back-scatter diffraction. The VDZ widths at Sigma 3 < 1 1 0 > tilt GBs ranged from 0 to 24 nm and increased with the GB plane inclination angle. For non-Sigma 3 GBs, VDZ widths ranged from 40 to 70 nm and generally increased with misorientation angle. Nevertheless, there is considerable scatter about this general trend, indicating that the remaining crystallographic parameters also play a role in determining the sink efficiencies of these GBs. In addition, the VDZ widths at two sides of a GB show different values for certain asymmetrical GBs. Voids were also observed within GB planes and their density and radius also appeared to depend on GB character. We conclude that GB sink efficiencies depend on the overall GB character, including both misorientation and GB plane orientation. Published by Elsevier Ltd. on behalf of Acta Materialia Inc.

We report on an experimental and simulation campaign aimed at exploring the radiation response of nanoporous Au (np-Au) foams. We find different defect accumulation behavior by varying radiation dose-rate in ion-irradiated np-Au foams. Stacking fault tetrahedra are formed when np-Au foams are irradiated at high dose-rate, but they do not seem to be formed in np-Au at low dose-rate irradiation. A model is proposed to explain the dose-rate dependent defect accumulation based on these results.

We report on an experimental and simulation campaign aimed at exploring the radiation response of nanoporous Au (np-Au) foams. We find different defect accumulation behavior by varying radiation dose-rate in ion-irradiated np-Au foams. Stacking fault tetrahedra are formed when np-Au foams are irradiated at high dose-rate, but they do not seem to be formed in np-Au at low dose-rate irradiation. A model is proposed to explain the dose-rate dependent defect accumulation based on these results. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4764528]

Fe films with an average columnar grain size varying from 49 to 96 nm are deposited by magnetron sputtering technique. Sputtered films have predominant body centered cubic structure together with a small fraction of face centered cubic phase. Bulk Fe with an average grain size of 700 nm is also irradiated at the same condition for comparison. Helium bubbles are observed in Fe films and bulk Fe irradiated by 100 keV helium ions to a fluence of 6 x 10(20) ions/m(2) at room temperature. Smaller grains lead to lower density of He bubbles. Radiation hardening in Fe films is much less than that of bulk Fe, and is a combined consequence of He bubble induced hardening and radiation induced compressive stress in Fe films. (c) 2011 Elsevier B.V. All rights reserved.

Application of metallic glasses as structural materials has been limited by their poor ductility. To overcome brittle failure, nanocrystals are intentionally introduced to stabilize the glasses. In this study, we report on the application of ion irradiation to induce nanocrystalization in a Cu(50)Zr(45)Ti(5) (CZT) alloy. Transmission electron microcopy, microindentation and nanoindentation have been used to characterize the CZT alloy irradiated with 140 keV He ions at room temperature. Hardness enhancement was observed near the projected range of the He ions, coinciding with the formation of nanocrystals. Such microstructural changes, however, were not observed in the near surface region, where the electronic stopping process is dominant. (C) 2009 Elsevier B.V. All rights reserved.

Metallic multilayers are good model systems to explore the effects of heterophase interfaces in reducing radiation damage in structural materials We summarize recent studies on radiation damage in immiscible face centered cubic/body-centered cubic metallic multilayers in particular Cu/V and Cu/Nb These multilayers have shown unique characteristics compared to bulk metals under irradiation, including several orders of magnitude higher He solid solubility dramatic reduction of bubble density interface confined growth of He bubbles and much lower radiation hardening The mechanisms for interface enhanced radiation tolerance are briefly discussed

Sputter-deposited Cu/V nanolayer films with individual layer thickness, h, varying from 1 to 200 nm were subjected to helium (He) ion irradiation at room temperature. At a peak dose level of 6 displacements per atom (dpa), the average helium bubble density and lattice expansion decrease significantly with decreasing h. The magnitude of radiation hardening decreases with decreasing individual layer thickness, and becomes negligible when h is 2.5 nm or less. This study indicates that nearly immiscible Cu/V interfaces spaced a few nm apart can effectively reduce the concentration of radiation induced point defects. Consequently, Cu/V nanolayers possess enhanced radiation tolerance, i.e., reduction of swelling and suppression of radiation hardening, compared to monolithic Cu or V. (C) 2010 Elsevier B.V. All rights reserved.

The electrical resistivity of sputter-deposited Cu/V multilayer films with different individual layer thicknesses varying from 2.5 to 100 nm was evaluated in the temperature range of 150-300 K. The temperature coefficient of resistivity (TCR) of Cu/V multilayer was compared based on the semi-classical theory of Dimmich model. A new model has been proposed to describe the relationship between the resistivity and the individual layer thickness of metallic multilayer film by considering both interface scattering and grain boundary scattering based on Fuchs-Sondheimer method and Mayadas-Shatzkes method. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

We studied the effect of irradiation on small angle grain boundaries in mosaic structured Cu thin films. The films showed a decrease in mosaic spread via a narrowing of the full width at half maximum in XRD rocking curves and a smaller minimum yield of RBS channeling after irradiation. These data indicate the irradiation decreased the misorientation angles between mosaic blocks separated by small angle grain boundaries. Mechanisms involving interactions between grain boundary dislocations and irradiation induced defects are discussed.

We studied the effect of irradiation on small angle grain boundaries in mosaic structured Cu thin films. The films showed a decrease in mosaic spread via a narrowing of the full width at half maximum in XRD rocking curves and a smaller minimum yield of RBS channeling after irradiation. These data indicate the irradiation decreased the misorientation angles between mosaic blocks separated by small angle grain boundaries. Mechanisms involving interactions between grain boundary dislocations and irradiation induced defects are discussed.

We have investigated the microstructure and mechanical properties of sputter-deposited Cu/V and Al/Nb metallic multilayer systems in this study and compared their mechanical properties to Cu/Cr and Cu/Nb reported earlier. These multilayer films are all of fcc/bcc type, with Kurdjumov-Sachs orientation relationship: {111}fcc//{110}bcc; < 110 > fcc//< 111 > bcc. In all cases, hardnesses of multilayers increase with decreasing layer thickness, and reach maxima at approximately 2-5 nm layer thickness. The differences in their mechanical properties (the Hall-Petch slope and peak hardness) are interpreted in terms of their differences in shear moduli, heat of mixing, and characteristics of interfaces. (C) 2007 Elsevier B.V. All rights reserved.

We studied the frequency shifts in G, D and D' Raman modes in freestanding multiwall carbon nanotube buckypapers. Upon ion irradiation by 140 keV He(+) or 3 MeV H(+) ions, the intensity ratio of D-G modes linearly increases with fluence before amorphization. The ratio is used to quantitatively measure the level of disorder in the buckypaper. The study shows that, upon post-irradiation annealing, defect removal requires little energy addition in lightly damaged buckypaper, which is evidenced by an activation energy of 0.36 eV. Once amorphized. defect removal becomes very difficult. The D-G intensity ratio has no reduction in heavily damage sample after annealing up to 850 degrees C. (C) 2009 Elsevier B.V All rights reserved